Posterior stabilization systems and methods

ABSTRACT

An implantable body for a posterior stabilization system includes a lateral end, a medial end, an inwardly facing surface configured to abut against a lamina when the body is implanted along a vertebra. A lateral bone outrigger extends from the inwardly facing surface and may include a bone-abutting surface along a medial portion disposed to abut against a lateral mass of the vertebra when the body is implanted along a vertebra. The lateral bone outrigger may have a first height. A penetrating feature extends from the inwardly facing surface between the bone-engaging portion of the inwardly facing surface and the lateral bone outrigger. The penetrating feature may have a second height less than the first height. A fastener bore extends through the body at an angle toward the lateral bone outrigger.

PRIORITY

This patent application claims priority to and the benefit of the filingdate of U.S. Provisional Patent Application 61/708,384, filed Oct. 1,2012, titled “Posterior Stabilization System and Method,” which isincorporated herein by reference. This patent application also claimspriority to and is a continuation in part application of InternationalApplication PCT/US2012/031922, filed Apr. 2, 2012, titled “PosteriorCervical Stabilization System and Method,” which claims priority to andthe benefit of the filing date of U.S. Provisional Patent Application61/470,885, filed Apr. 1, 2011, both of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present disclosure relates to devices, systems, and methods forstabilizing posterior elements of the spine. More particularly, thedisclosure relates to posterior stabilization devices, systems, andmethods that may secure to the cervical and thoracic spine.

BACKGROUND

The vertebrae in a patient's spinal column are linked to one another bythe disc, ligaments and the facet joints. The facet joints controlmovement of the vertebrae relative to one another. Each vertebra has apair of articulating surfaces located on the left or right side, andeach pair includes a superior articular process and an inferiorarticular process. Together the superior and inferior articular surfacesof adjacent vertebra form a facet joint. Facet joints are synovialjoints, which means that each joint is surrounded by a capsule ofconnective tissue and produces a fluid to nourish and lubricate thejoint. The joint surfaces are coated with cartilage allowing the jointsto move or articulate relative to one another.

Facet joints and/or discs that become diseased, degenerated, impaired,or otherwise painful can require surgery to stabilize the joint.Traditionally, diseased levels in the spine were fused to one another.While such a technique may relieve pain, the fusing effectively preventsmotion between at least two vertebrae. As a result of the limitedmotion, additional stress may be applied to the adjoining levels,thereby potentially leading to further damage to the spine.

Multiple techniques have been used in the past to stabilize the spine,including the cervical spine, from a posterior approach to the boneyelements. Such approaches have included minimally invasive techniques.Despite these attempts, there remain difficulties in safe placement ofexisting fixation devices, particularly on small cervical bones, as wellas difficulties in achieving solid fixation with minimal disruption tosurrounding tissue.

The present disclosure is directed to devices, systems, and methods thataddress one or more deficiencies in the prior art.

SUMMARY

According to various aspects of the disclosure, a posteriorstabilization system may be secured to associated occipital C₁, C₂, andthoracic spine portions. The system may be modular such that it can beattached to the skull or, using fluoroscopic imaging, can be placed atC₁ C₂. The system may include jigs or modules configured for useprimarily with the lateral masses of the cervical spine C₃-C₆ or, withthe secured variation, for use with the C₇ pedicles or the thoracicpedicles. Thus, the system could be used from the skull through theTspine.

The C₃-C₆ lateral mass modules would contain a pre-drilled hole withorientation of about 20-40° laterally (away from the spinal cord) androstrally about 20-40° (toward the head). The module can be held by anintroducer instrument as a fork device (e.g., top-loading) that cansecure the position of the jig or module in conjunction with tiny spikeson the bottom of the modules prior to holes being drilled in the bone,for example, with a tap, and final fixation with a screw, such as atitanium screw. The modules can be secured to a rod laterally with toploading nuts. The lateral mass modules could then be secured tooccipital C₁, C₂, C₇ thoracic with screws. The C₇ or thoracic modulesare oriented with pre-drilled holes about 10-15° medially.

In an exemplary aspect, the present disclosure is directed to aposterior stabilization system that includes a rod; a plurality ofmodules configured to be coupled with the rod, each of the modulesincluding a pre-drilled hole for providing a predetermined orientationfor a screw to be associated with the module; and a screw associatedwith each module, the screws extending through the respective modulesand extending from the module in said predetermined orientation. In oneaspect, the system includes a plurality of securing members, eachsecuring member cooperating with one of said modules to fixedly positionthe module on the rod.

In another exemplary aspect, the present disclosure is directed to animplantable body for a posterior stabilization system that includes alateral end, a medial end, an inwardly facing surface, and an outwardlyfacing surface. The inwardly facing surface has a bone-abutting portiondisposed proximate the medial end and configured to abut against alamina when the body is implanted along a vertebra. The system alsoincludes a lateral bone outrigger extending from the inwardly facingsurface adjacent the lateral end. The lateral bone outrigger has abone-abutting surface along a medial portion disposed to abut against alateral mass of the vertebra when the body is implanted along avertebra. The lateral bone outrigger has a first height. A penetratingfeature extends from the inwardly facing surface between thebone-engaging portion of the inwardly facing surface and the lateralbone outrigger. The penetrating feature has a second height less thanthe first height. A fastener bore extends through the body from theinwardly facing surface to the outwardly facing surface, and is angledtoward the lateral bone outrigger.

In an aspect, the inwardly facing surface comprises a tapered surfaceand a flat surface, the bone-abutting portion being formed of thetapered surface. In an aspect, the inwardly facing surface comprises acurved surface and a flat surface, the bone-abutting portion beingformed of the curved surface. In an aspect, the bone-abutting surface onthe lateral bone outrigger is a rounded surface. In an aspect, thefastener bore is angled at an angle within the range of about 20-55degrees when measured in cross-section. In an aspect, the fastener boreis angled at an angle within the range of about 20-55 degrees asmeasured from a side edge. In an aspect, the second height from theinwardly facing surface is within a range of about 4-8 mm. In an aspect,the lateral bone outrigger is cylindrically shaped and is disposedproximate only a portion of the lateral end. In an aspect, the lateralbone outrigger is disposed in a corner of the inwardly facing surface.In an aspect, the lateral bone outrigger is disposed along a centerlineextending from the medial end to the lateral end. In an aspect, thefastener bore is angled so that when the implantable is implanted, thefastener bore forms an angle in the range of 20-55 degrees from thesagittal plane and an angle in the range of 20-55 degrees from the axialplane.

In another exemplary aspect, the present disclosure is directed to aposterior stabilization system that includes an implantable body shapedto abut against a lateral mass of a cervical vertebra. The body includesa lateral end, a medial end, an inwardly facing surface and an outwardlyfacing surface. The inwardly facing surface has a bone-abutting portiondisposed proximate the medial end configured to abut against a laminawhen the body is implanted along a vertebra. The body also includes alateral bone outrigger extending from the inwardly facing surfaceadjacent the lateral end, the lateral bone outrigger having abone-abutting surface at along a medial portion disposed to abut againsta lateral mass of the vertebra when the body is implanted along avertebra. The body also includes a penetrating feature extending fromthe inwardly facing surface between the bone-engaging portion of theinwardly facing surface and the lateral bone outrigger, the penetratingfeature having a second height less than the first height; and includesa fastener bore extending through the body from the inwardly facingsurface to the outwardly facing surface. The system includes a rodreceiving portion sized to receive a fixation rod, the rod receivingportion being pivotably attached to the body and includes a fastenersized to extend through the bore and penetrate the lateral mass of thevertebra.

In an aspect, the inwardly facing surface comprises a tapered surfaceand a flat surface, the bone-abutting portion being formed of thetapered surface. In an aspect, the inwardly facing surface comprises acurved surface and a flat surface, the bone-abutting portion beingformed of the curved surface. In an aspect, the bone-abutting surface onthe lateral bone outrigger is a rounded surface. In an aspect, thefastener bore is angled at an angle within the range of about 20-55degrees when measured in cross-section. In an aspect, the fastener boreis angled at an angle within the range of about 20-55 degrees asmeasured from a side edge. In an aspect, the lateral bone outrigger hasa height above the inwardly facing surface within a range of about 4-8mm. In an aspect, the lateral bone outrigger is cylindrically shaped andis disposed proximate only a portion of the lateral end. In an aspect,the lateral bone outrigger is disposed in a corner of the inwardlyfacing surface. In an aspect, the lateral bone outrigger is disposedalong a centerline extending from the medial end to the lateral end. Inan aspect, the fastener is a bolt. In an aspect, the rod receivingportion is integrally formed with the body. In an aspect, the fastenerbore is angled so that when the implantable is implanted, the fastenerbore forms an angle in the range of 20-55 degrees from the sagittalplane and an angle in the range of 20-55 degrees from the axial plane.

In another exemplary aspect, the present disclosure is directed to anon-pedicle based fixation system. The system includes a first posteriorstabilization system that includes a first body shaped to abut against alateral mass of a first cervical vertebra, the first body including alateral end, a medial end, an inwardly facing surface, and an outwardlyfacing surface, the inwardly facing surface having a bone-abuttingportion disposed proximate the medial end and configured to abut againsta lamina when the body is implanted along a vertebra; a lateral boneoutrigger extending from the inwardly facing surface adjacent thelateral end, the lateral bone outrigger having a bone-abutting surfaceat along a medial portion disposed to abut against a lateral mass of thevertebra when the body is implanted along a vertebra; and a penetratingfeature extending from the inwardly facing surface between thebone-engaging portion of the inwardly facing surface and the lateralbone outrigger, the penetrating feature having a second height less thanthe first height. A first rod receiving portion is shaped to receive afixation rod, the rod receiving portion being disposed closer to thelateral end than the medial end. A second posterior stabilization systemincludes a second body shaped to abut against a lateral mass of a secondcervical vertebra, the first body comprising: a lateral end, a medialend, an inwardly facing surface, and an outwardly facing surface, theinwardly facing surface having a bone-abutting portion disposedproximate the medial end and configured to abut against a lamina whenthe body is implanted along a vertebra; a lateral bone outriggerextending from the inwardly facing surface adjacent the lateral end, thelateral bone outrigger having a bone-abutting surface at along a medialportion disposed to abut against a lateral mass of the vertebra when thebody is implanted along a vertebra; a penetrating feature extending fromthe inwardly facing surface between the bone-engaging portion of theinwardly facing surface and the lateral bone outrigger, the penetratingfeature having a second height less than the first height; and a secondrod receiving portion shaped to receive the fixation rod, the rodreceiving portion being disposed closer to the lateral end than themedial end; and a fixation rod disposed within the first and second rodreceiving portions.

In an aspect, the first body comprises a fastener bore extending throughthe body from the inwardly facing surface to the outwardly facingsurface, the fastener bore being angled toward the lateral boneoutrigger. In an aspect, the first body includes a side edge, thefastener bore being angled away from the side edge. In an aspect, thefastener bore is angled toward the lateral bone outrigger within anangle range of about 20-55 degrees, and the fastener bore angled awayfrom the side edge within an angle range of about 20-55 degrees.

In another exemplary aspect, the present disclosure is directed to asurgical method comprising: introducing a body portion to a firstvertebra so that an inwardly facing surface proximate a medial end abutsa lamina of the vertebra and so that a lateral bone outrigger extendingfrom the inwardly facing surface adjacent the lateral end abuts againsta lateral side of the lateral mass of the vertebra; driving a fastenerin a lateral direction toward the lateral bone outrigger and into thelateral mass through a fastener bore extending through the body portion;and inserting a fixation rod in a rod receiver associated with the bodyportion so that the rod is disposed lateral of the fastener bore.

In an aspect, the method includes forming a pilot hole in the lateralmass through the body portion before driving the fastener, the holebeing formed in the lateral mass in a direction toward the lateral boneoutrigger. In an aspect, the method includes applying loading againstthe body portion to drive penetrating features on the body portion intothe lamina.

In another exemplary aspect, the present disclosure is directed to animplantable body for a posterior stabilization system including alateral end, a medial end, an inwardly facing surface, and an outwardlyfacing surface, the inwardly facing surface having a bone-abuttingportion disposed proximate the medial end and configured to abut againsta lamina when the body is implanted along a vertebra; a lateral boneoutrigger extending from the inwardly facing surface adjacent thelateral end, the lateral bone outrigger having a bone-abutting surfaceat along a medial portion disposed to abut against a lateral mass of thevertebra when the body is implanted along a vertebra, the lateral boneoutrigger having a first height; a penetrating feature extending fromthe inwardly facing surface between the bone-engaging portion of theinwardly facing surface and the lateral bone outrigger, the penetratingfeature having a second height less than the first height; and afastener bore extending through the body from the inwardly facingsurface to the outwardly facing surface.

In an aspect, the fastener bore is angled toward the lateral boneoutrigger. In an aspect, the fastener bore is angled at an obliqueangle.

In some aspects of the systems disclosed herein, the outrigger is angledin the lateral direction from the jig. In some aspects, the inwardlyfacing surface includes a convex portion and a concave portion, theconvex portion being near the medial end and the concave portion beingnear the lateral end. In some aspects, a head and post extend from thejig, and a receiver is configured to pivot about the head.

Some further advantages and embodiments may become evident from theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures.

FIG. 1 is a top view of an exemplary posterior cervical stabilizationsystem in accordance with various aspects of the disclosure.

FIG. 2 is a bottom view of an exemplary posterior cervical stabilizationsystem in accordance with various aspects of the disclosure.

FIG. 3 is a lateral view of an exemplary posterior cervicalstabilization system in accordance with various aspects of thedisclosure.

FIG. 4 is a top view of an exemplary posterior cervical stabilizationsystem in accordance with various aspects of the disclosure.

FIGS. 5-6 are alternate views of the exemplary system of FIG. 2.

FIG. 7 is a top view of another exemplary posterior cervicalstabilization system in accordance with various aspects of thedisclosure.

FIG. 8 illustrates a perspective view of another exemplary posteriorcervical stabilization system in place on a vertebra in accordance withvarious aspects of the disclosure.

FIG. 9 illustrates a perspective view of the exemplary posteriorcervical stabilization system of FIG. 8 in place on a vertebra showinghidden lines representing features of the system in accordance withvarious aspects of the disclosure.

FIG. 10 illustrates a top view of the exemplary posterior cervicalstabilization system of FIG. 8 in place on a vertebra in accordance withvarious aspects of the disclosure.

FIG. 11 illustrates a side view of the exemplary posterior cervicalstabilization system of FIG. 8 in place on a vertebra showing hiddenlines representing features of the system in accordance with variousaspects of the disclosure.

FIG. 12 illustrates an isometric view of an exemplary posterior cervicalstabilization system in accordance with various aspects of thedisclosure.

FIG. 13 illustrates an isometric view of the exemplary posteriorcervical stabilization system of FIG. 12 in accordance with variousaspects of the disclosure.

FIGS. 14A-14E illustrate views of an exemplary jig of the posteriorcervical stabilization system of FIG. 12 in accordance with variousaspects of the disclosure.

FIG. 15 illustrates an isometric view of an exemplary fastener of theposterior cervical stabilization system of FIG. 12 in accordance withvarious aspects of the disclosure.

FIGS. 16A-16C illustrate views of an exemplary receiver of the posteriorcervical stabilization system of FIG. 12 in accordance with variousaspects of the disclosure.

FIG. 17 illustrates an isometric view of an exemplary set screw of theposterior cervical stabilization system of FIG. 12 in accordance withvarious aspects of the disclosure.

FIGS. 18A-18E illustrate views of an exemplary jig of the posteriorcervical stabilization system in accordance with various aspects of thedisclosure.

FIGS. 19A-19D illustrates views of an exemplary jig of the posteriorcervical stabilization system in accordance with various aspects of thedisclosure.

FIGS. 20A-20D illustrate views of an exemplary jig of the posteriorcervical stabilization system in accordance with various aspects of thedisclosure.

FIGS. 21A-21C illustrate views of an exemplary jig of the posteriorcervical stabilization system in accordance with various aspects of thedisclosure.

FIGS. 22A and 22B illustrate views of an exemplary surgical instrumentof the posterior cervical stabilization system in accordance withvarious aspects of the disclosure.

FIGS. 23 and 24 illustrate opposing side views of another posteriorcervical stabilization system in accordance with various aspects of thedisclosure.

FIGS. 25 and 26 illustrate views of a jig with a pivot head of theposterior cervical stabilization system of FIGS. 23 and 24 in accordancewith various aspects of the disclosure.

FIG. 27 illustrates an isometric view of a jig with a pivot head and afastener of the posterior cervical stabilization system of FIGS. 23 and24 in accordance with various aspects of the disclosure.

FIG. 28 illustrates a top view of the exemplary posterior cervicalstabilization system of FIGS. 23 and 24 in place on a vertebra inaccordance with various aspects of the disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of various embodiments.Specific examples of components and arrangements are described below tosimplify the present disclosure. These are, of course, merely examplesand are not intended to be limiting. In addition, the present disclosuremay repeat reference numerals and/or letters in the various examples.This repetition is for the purpose of simplicity and clarity and doesnot in itself dictate a relationship between the various embodimentsand/or configurations discussed.

FIG. 1 illustrates an exemplary posterior stabilization system inaccordance with the disclosure. A posterior cervical stabilizationsystem 100 may include two or more jigs or modular components 102, 104,106 with a top loading rod 110. Although the illustrated embodimentsshow systems 100 have two and three modules, it should be appreciatedthat the systems contemplated by this disclosure may include any numberof modules.

The modules 102, 104, 106 are oriented on the lateral masses withfixation with titanium screws into the bone of the lateral mass with anorientation outward about 20-40° and angulation rostrally about 20-40°.The modules 102, 104, 106 have a low profile and either lock to theinterphase of the module or are held with a locking mechanism. Thelaterally held rod 110 can be polyaxial or non-polyaxial with itsconnection to the modules with a top loading nut.

As shown in FIG. 1, module 102 may be oriented medially about 10-15° andused with a C₇ or thoracic screw. Modules 104, 106 are the lateral masscomponents oriented laterally about 20-40° and rostrally about 20-40°.

Referring to FIG. 2, a bottom surface 220 of the modules 104, 106 mayinclude one or more small spikes 222, or example, 1-2 mm extensions fromthe bottom surface. The spikes 222 can be used to temporarily hold themodules to a lateral mass bone prior to the creation of screw holes forreceiving the screws. The bottom surface 220 of the modules 104, 106 mayalso include a lateral flange 224 oriented toward the lateral aspect ofthe lateral mass to help with centering the module 104, 106. Althoughnot depicted in FIG. 2, module 102 may similarly include spikes and alateral flange for holding and centering the module during a procedure.

Referring now to FIG. 3, the module 102 includes the C₇ or thoracicscrew 330 oriented about 10-15° medially. The modules 104, 106 includethe lateral mass screws 332, 334, which are oriented about 20-40°laterally and about 20-40° rostrally away from the spinal cord.

The modules 102, 104, 106 are individually oriented over the center ofthe lateral mass, and each includes a predrilled hole with appropriatelateral and rostral orientation. Accordingly, the modules 102, 104, 106can be held and holes can be drilled, tapped, and the screws fixated andlocked to the modules.

The rod 110 may be formed of titanium, polyethylene ketone (PEEK),carbon fiber, or other suitable composites that provide the desiredcharacteristics of flexibility/stiffness, biocompatibility, imagingcharacteristic, and the like. The modules 102, 104, 106 include atop-loading polyaxial or non-polyaxial screw top 336 that receives therod 110. The rod 110 can be secured to the modules with top loading nuts338 that couple with the screw tops 336. It should be appreciated thatother conventional securing mechanisms are contemplated by thisdisclosure.

FIG. 4 illustrates the stabilization system 350 during an exemplaryimplantation procedure. The system 350 includes a top-loading introducerfork device 352 that can straddle a module 354 and couple with themodule via engagement with grooves 356 in the sides of the module 354.The fork device 352 can thus temporarily secure the positioning of themodule during drilling and placement of the screws.

FIGS. 5 and 6 illustrate different views of the system shown in FIG. 2so that additional aspects and features of the disclosure can beappreciated. FIG. 7 illustrates an alternative stabilization system 370where the modules 372, 374, 376 are fixedly coupled to one another viaconnecting elements 378, 380 rather than via a rod.

This posterior cervical stabilization system is better than otherconventional system because this system is able to produce morereproducible screw angles, which promotes more safety.

FIGS. 8-13 illustrate another exemplary embodiment of a posteriorcervical stabilization system, referenced herein by the numeral 400. Thesystem includes a jig 402, a fastener 404 (FIG. 11) configured to anchorthe jig 402 to a bone construct, a rod connector 406, and a set screw408 (shown in FIGS. 12 and 17). In the embodiment shown, the system 400is attached along a lamina of a cervical vertebra to provide an anchorfor a rod 409 (shown in FIGS. 12 and 13) that is received in the rodconnector 404. The illustrated vertebra represents a C2 segment and hasa pedicle P and a lateral mass LM. As illustrated, the jig 400 extendsacross the top of the pedicle P and engages the lateral mass LM. Thefastener 404 (shown in dash in FIG. 11) extends laterally away from thespinal midline to engage bone within the lateral mass LM. In theillustrated embodiment, the fastener trajectory is substantiallytransverse to the pedicle longitudinal axis LP.

FIGS. 12 and 13 show the system independent of the bone structure itselfin an assembled condition with FIG. 12 showing an internally facing sideor bottom side, and FIG. 13 showing the outwardly facing side or topside. Although the rod connector 406 differs slightly in appearancebetween FIGS. 8-11 and 12-13, for ease of understanding, the samereference numbers are used. FIGS. 14A-14E show the jig 402 in greaterdetail. The jig 402 is formed, in this embodiment, of a solid rigidmaterial and is formed substantially as a block or body having a numberof protrusions extending therefrom. The jig 402 includes an outwardlyfacing or top side 418, an inwardly facing side or bottom side 420, twoside edges 422 a, 422 b, a medial end 424 configured to be mediallydisposed when implanted on a vertebra, and a lateral end 426 configuredto be laterally disposed when implanted on a vertebra as shown in FIGS.8-11. Since some embodiments of the jig 402 are configured to beimplanted along the cervical vertebrae, the jig is sized to fit to thevertebra and to be relatively discreet after implantation. Therefore,some embodiments of the jig 402 have a length from the medial end 424 tothe lateral end 426 in the range of about 10-22 mm, a width from theside edge 422 a to side edge 422 b in the range of about 6-15 mm, and aheight between the flat outwardly facing surface 418 to the flatinwardly facing surface 420 of about 4-10 mm. In other embodiments, thelength is in the range of about 14-18 mm, the width is in the range ofabout 8-12 mm, and the height is in the range of about 5-7 mm. In oneembodiment, the length is 16 mm, the width is 10 mm, and the height is 6mm. However, other embodiments have dimensions greater and smaller thanthose identified herein.

The outwardly facing side 418 is substantially flat and includes afastener opening 428 leading to a through bore 430 for receiving thefastener 404. In the exemplary embodiment shown, the outwardly facingside includes an opening 432 to a rod connector attachment feature 433for affixing the rod connector 406. In this example, as will bedescribed further below, the bore 430 is formed at an oblique anglethrough the jig 402. As such, the fastener opening 428 is oval shaped,and the fastener opening 428 intersects with the medial end 424. In oneembodiment, the opening 428 has a diameter measured along the bore 430of about 6.4 mm, although other sizes, larger and smaller are alsocontemplated.

Each side edge 422 a, 422 b includes an instrument engaging feature 434sized and arranged to interface with an introducer instrument (describedbelow). In this embodiment, in order to reduce the likelihood ofslippage along the jig 402, the instrument engaging feature 434 is aslot-like indentation extending along each side edge 422 a, 422 b fromthe outwardly facing side 418 toward the inwardly facing side 420. Theinstrument engaging feature 434 has open end at the outwardly facingside 418 and a closed end 436. As such, the instrument is less likely toslip even if the surgeon applies loading toward the bone construct bypressing the internally facing side 420 against a vertebra. In theexample shown, the instrument engaging features 434 are disposed closerto the lateral end 426 than the medial end 424. This places theinstrument engaging features 434 closer in proximity to protrudingfeatures on the inwardly facing side 420 and may enable easy access tothe fastener opening 428 for the placement of the fastener 404. Here,they are aligned with protruding features and the rod connector featureopening 432. However, other embodiments have the instrument engagingfeatures 434 disposed centrally or even toward the medial end 424.

Since the embodiment of the jig 402 shown in FIGS. 12-14 is configuredand arranged for implantation on the cervical vertebra, some embodimentsare minimally sized in order to make the implant as discrete as possibleon the patient's neck. In the embodiment shown, and as described above,the fastener opening 428 is sized and disposed to intersect the medialend 424. As such, the bore 430 also intersects the lateral end,providing a recessed arc 438 in the lateral end.

The bottom or inwardly facing side 420 includes a relatively planarsurface portion 446 and a relatively tapered surface portion or curvedsurface portion 448. The curved surface portion 448 is disposed towardthe medial end 424 of the jig 402 and curves from the flat surfaceportion to the intersection of the inwardly facing side 420 and themedial end 424. In some embodiments the radius of curvature is withinthe range of about 5-20 mm. In other embodiments, the radius ofcurvature is within a range of about 8-12 mm. Further, the curvedsurface portion intersects the planar surface portion at a locationabout 50-80% of the distance from the lateral end 426. The curvedsurface portion 448 is a bone abutting portion located and shaped toabut against the lamina of the vertebra.

A plurality of protruding features extends from the planar surfaceportion 446 and is configured to engage and help locate the jig 402 onthe vertebra. In the embodiment shown, the protruding features includeone or more penetrating features 450 and one or more lateral boneoutriggers 452. The embodiment in FIGS. 14A-14E includes threepenetrating features 450 and a single lateral bone outrigger 452.However, other numbers of features could be used to achieve desiredfunctionality. The penetrating features 450 in this embodiment areformed as conical spikes that extend to a sharp point. These areconfigured to engage against and penetrate the bone structure when thejig 402 is in place against the lamina and/or lateral mass of thevertebra. In the embodiment shown, at least two of the penetratingfeatures are disposed on opposite sides (but extending from the inwardlyfacing side 420) of the attachment feature opening 432, as can be seenin the bottom view of the jig 104 in FIGS. 14A-14E. In this embodiment,the penetrating features 450 are located within the range of about 2-13mm from the lateral end 426. In some embodiments, the penetratingfeatures 450 disposed on opposing sides of the attachment feature andare about 4-7 mm from the lateral end 426. In addition, in someembodiments, at least two penetrating features 450 are disposed equaldistances from and on opposing sides of a centerline through the jig 402extending from the medial end 424 to the lateral end 426. In thisembodiment, the penetrating features 450 have a height that is less thana height of the lateral bone outrigger 452. For example, the penetrationfeatures 450 may have a height in the range of about 50-75% of theheight of the lateral bone outrigger 452. In one embodiment, thepenetrating features have a height about 3.5 mm from the planar surfaceportion 446.

The lateral bone outrigger 452 is configured to abut against bonestructure as shown in FIG. 8-11. In this embodiment, the lateral boneoutrigger 452 is configured to rest against the exterior surface of thelateral mass and includes a smooth abutting surface and is devoid of asharp point or edge. The lateral bone outrigger 452 is disposedproximate the lateral end 426, and in the embodiment shown, is flushwith the lateral end 426. It has a bone-abutting surface 454 disposed ona medial side or along a top medial/medial side that is configured torest against the bone to provide lateral support to the jig 402 when thejig is implanted. Because of the curvature of the lateral mass (as seenin FIG. 8), the bone-abutting portion 454 is in part on the bottomand/or medial side of the lateral bone outrigger 452. In someembodiments, it is formed by a chamfer or round connecting the end andthe medial sides of the lateral bone outrigger 452. The lateral boneoutrigger 452 also has a height greater than that of the penetratingfeatures 450 so that it can engage the perimeter of the lateral masseven while the jig 404 does not follow the curvature of the lamina andlateral mass, as can be seen in FIG. 11. For example, the lateral boneoutrigger 452 may have a height in the range of about 4-8 mm, and morepreferably, about 5-6 mm. However, other heights, both larger andsmaller are contemplated. Because of its height and arrangement, thelateral bone outrigger 452 and inwardly facing surface may create a gapbetween the bone and the jig 402. As such, when properly implanted thejig 404 may operate as a simple beam with the jig abutting against thebone at the medial portion and at the lateral portion, such that loadingagainst the bone occurs at the medial portion and at the lateralportion, but much less so between these portions where the penetrationfeatures are disposed. The fastener may then apply opposite loading inthe region between the abutting portions.

The embodiment shown in FIGS. 14A-14E includes the lateral boneoutrigger 452 as a wall extending from the planar surface portion,substantially flush with the lateral end 426, and extending from one ofthe side edges 422 a, 422 b toward the other. However, as can be seen,in the exemplary embodiment shown, the lateral bone outrigger 452 doesnot extend across the width and extends only just beyond the midline.

The bore 430 is disposed at an angle and extends from the outwardlyfacing surface 418 to the inwardly facing surface 420. It has alongitudinal axis and is sized and configured to receive the fastener404 and direct the fastener 404 into the lateral mass of the vertebra.Accordingly, instead of being angled toward the pedicle, as do somedevices, the bore 430 is disposed so that the angle directs the fastener404 in a direction either somewhat perpendicular to or oblique to thepedicle. As such, the bore 430 extends in the direction of the lateralbone outrigger 452. The bore position may be determined by taking intoaccount three angles: A1, A2, and A3, each labeled in FIGS. 14A-14E. Inthe embodiment shown, a cross-section through the bore 430 shows thebore 430 is angled at an angle A1 within a range of about 20-55 degreesfor example. In some embodiments, the angle A1 is within a range ofabout 25-45 degrees, and in yet other embodiments, the angle A1 iswithin a range of about 26-41 degrees. Some embodiments have an angle A1about 27 degrees, while other embodiments have an angle A1 of about 40degrees.

In addition, in the embodiment shown the bore 430 is angled relative tothe side 422 a at an angle A2 within a range of about 20-55 degrees forexample. In some embodiments, the angle A2 is within a range of about25-45 degrees, and in yet other embodiments, the angle A2 is within arange of about 26-41 degrees. Some embodiments have an angle A2 about 30degrees, while other embodiments have an angle A2 of about 40 degrees.In some embodiments, the angles A2 and A1 are within about 15 degrees ofeach other. In other embodiments, the angles A2 and A1 are within about10 degrees of each other. In the embodiment shown, the angles A2 and A1are within about 5 degrees of each other. In some embodiments, the boremay have an orientation of about 20-40° laterally (shown by angle A2,away from the spinal cord) and rostrally about 20-40° (shown by angleA1, toward the head).

These angles also may be described with reference to the vertebra asshown in reference to FIGS. 10 and 11. FIG. 10 shows the sagittal plane390 and the axial plane 392. FIG. 10 also shows a direction orlongitudinal axis 394 of the bore 430, which substantially correspondsto that of the implanted fastener 404 in FIG. 11. As can be seen, thelongitudinal direction of the bore 430 and fastener 404 is angled at theangle A2 from the axial plane 392, extending away from the sagittalplane 390 within a range of about 20-55 degrees. In some embodiments,the angle A2 is within a range of about 25-45 degrees, and in yet otherembodiments, the angle A2 is within a range of about 26-41 degrees.

FIG. 11 shows the angle of the bore 430 and fastener 404 looking intothe axial plane 392. As can be seen, the angle of the bore 430 andfastener 404 in this plane are within the range of a range of about20-55 degrees. In some embodiments, the angle A3 is within a range ofabout 25-45 degrees, and in yet other embodiments, the angle A3 iswithin a range of about 26-41 degrees. In one embodiment, the angle A3is 27 degrees. Angle A3 may also be measured from the medial side asshown in FIG. 14B. In addition, the rod connector 406 is disposedfurther from the axial plane 390 than the fastener 404, and the fastenerextends into the lateral mass and is angled in a direction nearlytransverse to the direction of the pedicle.

In the example shown the bore 430 is formed as a countersink bore sothat the head of the fastener 404 may recess within the bore, reducingthe chance of tissue trauma and providing an overall smoother profile.In some embodiments the bore 430 has a diameter between about 3-4 mmsized to fit a fastener that is suitable for engaging the lateral masswithout breaking out of the lateral mass. Some embodiments have a squarecounterbore instead of a taper counterbore.

The opening 432 to the attachment feature 433 is formed on the outwardlyfacing surface and is configured to receive and engage the rod connector406. The attachment feature 433 comprises a concave or sphericaldepression. In this example, the depression is disposed centrally alongthe centerline of the jig 402. It is configured as a sphericaldepression having a maximum inner diameter greater than the diameter ofthe opening 432 of the attachment feature 433. Accordingly, a lip isdefined at the outwardly facing surface that mechanically preventsremoval of a spherically shaped ball. In this example, the opening ofthe attachment feature 433 has a diameter of about 4.5-5.5 mm, althoughother sizes are contemplated. In one embodiment, the opening 432 has adiameter of about 4.8 mm and the diameter of the attachment feature 433is 5.0 mm. The center of the spherical depression may be spaced from theouter surface 418 by a distance in the range of about 0.5-1 mm, althoughother distances are contemplated.

It's worth noting that some embodiments include a right implant and aleft implant for use on the right or left sides of the vertebra. Thesemay be mirror images of each other.

FIG. 15 shows the fastener 404 in greater detail. In this embodiment,the fastener 404 is configured to perch within the lateral mass of thecervical vertebra. Therefore, the fastener in the embodiment shown as athread length of about 12 mm and a total length of about 14 mm.Accordingly, the fastener 404 may project further from the inwardlyfacing surface than the penetrating features 450 when measuredperpendicular from the inwardly facing surface as shown in FIG. 11,while the lateral bone outrigger 452 may project further from theinwardly facing surface than the fastener 404. As can be seen, thefastener 404 may include a tapered head 466 and a hex tool engagingrecess 468. In addition, the fastener 404 may have a cylindrical leadingend. Although the fastener 404 is shown as a bolt, other embodimentsinclude a fastener formed as a screw, a nail, a staple, or otherfastener.

FIGS. 16A-16C show the rod connector 406. In this embodiment, the rodconnector 406 is a separate element from the jig 402 and providesmulti-axial pivot capability to the system. It includes a pivot head 470and a U-shaped receiver 472, connected by a narrow neck 474. Alongitudinal centerline 476 extends through the head 470, neck 474, andreceiver 472.

The pivot head 470 is shaped as a spherical head having a flat band 480formed thereon, forming a cylindrical portion having a longitudinal axis482. The longitudinal axis 482 of the flat band 480 is disposed at anangle β relative to the centerline 476. In some embodiments, the angle βis within the range of about 20-40 degrees. In other embodiments, theangle β is within the range of about 28-35 degrees. In otherembodiments, the angle β is about 30 degrees. The spherical portion ofthe head 470 has a diameter sized greater than the opening 432 of theattachment feature 433, while the flat band 480 has a diameter sizedless than the opening 432 of the attachment feature 433. Accordingly,when the head 470 is angled so that flat band 480 lies in a planeparallel to the outwardly facing side 420 or parallel to the planedefined by the opening 432, the head 470 may pass through the opening432 of the attachment feature 433. With the head 470 within theattachment feature 433, the rod connector 406 may be pivoted so that theflat band 480 is not within a plane parallel to the outwardly facingside 420 or the opening 432. In this position, the head 470 is pivotablycaptured within the attachment feature 433 by virtue of the largerdiameter spherical portion. In addition, the head 470 may pivot withinattachment feature 432 so long as the band 480 does not become parallelto the outwardly facing side 420.

The receiver 406 is configured to receive a fixation rod. It is U-shapedwith two extending arms 490 connected a partially cylindrical bottomportion 492. The bottom portion 492 is configured to interface with thecurved outer surface of a cylindrical fixation rod as shown in FIGS. 12and 13. In the embodiments shown, the bottom portion 492 includes adiameter within a range of about 3-4 mm. In one example, the bottomportion 492 has a diameter of about 3.7 mm. Other sizes are alsocontemplated and the size of the bottom portion 492 may be selected tocorrespond to the expected size of the fixation rod. Other embodimentsinclude a bottom portion having a square shape, with teeth, or withother arrangements to engage the fixation rods. Each arm 490 of thereceiver 472 includes a threaded inner surface 494 configured to enablethreading of the set screw 408. The outer surface of the arms 490 maytaper in a conical manner. For example, the receiver 472 may have abottom region adjacent the neck having a larger diameter or size thanthe diameter or size of the receiver 472 along the top edge of the arms490. In one embodiment, the receiver has a diameter of about 8.5 mm atthe bottom region and about 7.7 mm at the top of the arms. The receiver472 may be sized so that the distance between the center of thespherical head 470 and the top of the arms 490 is within the range ofabout 8-15 mm. In one embodiment, the range is within about 11-13 mm.Again, since the system can be used on the cervical vertebrae, theheight limitations may be minimized. However other sizes, larger andsmaller may be utilized.

In the embodiment shown, the flat band 480 is aligned so that thereceiver 472 can tip forward and aft about the pivot head in thedirection of the longitudinal axis of a rod seated on the bottom portion492 within the receiver without concern for removal of the receiver fromthe jig 402.

FIG. 17 shows the set screw 408 in greater detail. It includes a hextool engaging recess 409 and is sized to thread between the arms 490 ofthe receiver 472 to capture a rod within the receiver and preventinadvertent removal.

It should be understood that although the systems disclosed herein arediscussed as being used with the cervical region of the spine, thesystems may be utilized in all regions of the spine, including thecervical, thoracic, lumbar, and lumbo-sacral regions. It should also beunderstood that the systems may extend across a spinal motion segmenthaving only two vertebrae or more than two vertebrae by combiningmultiple jigs with a fixation rod as shown in FIGS. 1-7 with each jigattached to a separate vertebra. In some embodiments, two or morestabilization systems may be employed simultaneously along the samespinal motion segment.

In some embodiments, the system 400 described above forms a part of aset of systems cooperate together to treat a spinal condition. Forexample, in some embodiments, multiple jigs 402 may be attached todifferent vertebrae, whether adjacent or not, and a fixation rod mayconnect all the jigs. Some embodiments include a plurality of jigs of aset each designed to fit one or more particular vertebrae. FIGS. 18-21show a plurality of different systems shaped for particular vertebraethat may be packaged, used, or sold as a set for treating a particularcondition. In addition, the jig 402 also may include as a part of a setin combination with these systems disclosed herein.

FIGS. 18A-18E show an exemplary alternative jig 600 usable on anyvertebra, but particularly suited for use on C2-C6 vertebrae, and FIGS.19A-19D show an exemplary jig 650 usable on any vertebra, butparticularly suited for use on a C7 vertebra. FIGS. 20A-20D show anexemplary jig 700 usable on any vertebra, but particularly suited foruse on C7 vertebra, and FIGS. 21A-21C show an exemplary jig 750 usableon any vertebra, but particularly suited for use on a T1 vertebra. Thejigs may be used with the fasteners, rod connector, and set screwsdisclosed above. Those descriptions will not be repeated here.

Referring first to FIGS. 18A-18E, the jig 600 include many featuressimilar to the jig 402 discussed above. Since the discussion aboveapplies, those discussions will not be repeated here. The jig 600however includes different protruding features, including differentpenetrating features 602 and a different lateral bone outrigger 604. Inthis embodiment, the penetrating features 602 are formed as extendingcylinders having pointed, conical ends. The pointed ends are configuredto penetrate the exterior of the lateral mass but because the angle ofthe conical end is less acute than the angle of the conical end of thepenetrating features 450 in FIG. 14A-14E, the system may be sturdierover time. In addition, loads applied laterally on the jig 600 mayresult in loading that is closer to a normal direction on thecylindrical surfaces of the penetrating features 602 in the bone than inthe conical surfaces of the penetrating features 450.

The lateral bone outrigger 604 in this embodiment is also a singlecylindrical feature. The cylindrical feature is disposed substantiallyalong the centerline of the jig 600. This lateral bone outrigger 604 hasa bone-abutting surface 606 on its medial side and/or end. The lateralbone outrigger 604 is formed with a radius between the sides and ends toprovide a smooth surface to abut against the lateral side of the lateralmass.

Also in this embodiment, the angle A1 may be in the range of about 30degrees and may correspond within a degree to the angle A2. These anglesmay vary as discussed with reference to the jig 402 above.

FIGS. 19A-19D show a jig 650 particularly shaped for use on C7 vertebra.The jig 650 is similar to those described above in many respects, butits bore is angled differently to accommodate the shape of the lateralmass of the C7 vertebra. In this embodiment, the angle A1 may be in therange of about 34 degrees and may correspond within less than about 10degrees to the angle A2. The angle A2 may be within a range of about35-45 degrees, and may about 40 degrees. These angles may vary asdiscussed with reference to the jig 402 above.

FIGS. 20A-20D show another embodiment of a jig 700 particularly shapedfor use on a C7 vertebra. Like the embodiments above, the jig 700includes protruding features that include penetrating features 702 andlateral bone outrigger 704 and a fastener bore, referenced herein by thenumeral 706. In this embodiment, the lateral bone outrigger 704 is acylindrical protrusion having a bone abutting surface 705 formed of aradius at an end that is configured to abut against the lateral mass asdescribed above. In this example however, the lateral bone outrigger 704protrudes at a corner of the inwardly facing surface. In this example,the cylindrical lateral bone outrigger surface is flush with both thelateral end 708 of the jig 700 and one of the side edges 710. This mayprovide additional stability to the jig on a C7 vertebra of particularpatients with a pedicle fastener in place of a lateral mass fastener.

Particularly, the jig 700 is formed so that the fastener bore 706 isangled away from the lateral bone outriggers 704. In this embodiment,the fastener bore opening 712 is contained entirely within the outwardlyfacing side and the bore 706 exits the inwardly facing side in thecurved surface portion 714.

In this embodiment, the angle A1 may be in the range of about 33 degreesand leading away from the lateral bone outrigger 704. Likewise, theangle A2 may be about 53 degrees. In the embodiment shown the bore 430is angled when taken in cross-section at an angle A1 within a range ofabout 20-55 degrees for example. In some embodiments, the angle A1 iswithin a range of about 25-45 degrees, and in yet other embodiments, theangle A1 is within a range of about 26-41 degrees. Some embodiments havean angle A1 about 32 degrees.

In addition, in the embodiment shown, the bore 712 is angled relative tothe side edge 710 b at an angle A2 within a range of about 30-65 degreesfor example. Here, the angles A2 and A3 may be negative angles whencompared to the embodiments discussed above. In some embodiments, theangle A2 is within a range of about 45-60 degrees, and in yet otherembodiments, the angle A2 is within a range of about 50-55 degrees. Someembodiments have an angle A2 about 53 degrees.

In addition, the overall width between side edges of the jig 700 islarger than the overall width between side edges of the jigs 600 and 650described above. In this example, the jig width may be within the rangeof about 6-15 mm, and in some embodiments within a range of 11-13 mm.

FIGS. 21A-21C show another embodiment of a jig 750 particularly shapedfor use on a T1 vertebra. Like the embodiments above, the jig 750includes protruding features that include penetrating features 752 and alateral bone outrigger 754 and a fastener bore, referenced herein by thenumeral 756. In this example however, since the jig 750 is shaped tocorrespond to the shape of a T1 vertebra, the lateral bone outrigger 754is disposed at an opposite side edge of the lateral end 758 of the jig750 at a corner of the inwardly facing surface. In this example, thecylindrical facing surface is flush with both the lateral end 708 of thejig 700 and one of the side edges 710. This may provide additionalstability to the jig on the T1 vertebra.

In addition, the fastener bore 756 is directed straight through orsubstantially perpendicular to the planes of the inwardly and outwardlyfacing surfaces. Accordingly, because of the shape of the T1 vertebra,the fastener may penetrate the pedicle of the T1 vertebra.

As described above, some embodiments include a set of jigs that mayinclude any two or more of the jigs and systems discussed above. In oneexample, the set may include a plurality of jigs including one or morejigs as shown in FIGS. 14A-14E or FIGS. 18A-18E, one or more jigs asshown in FIGS. 19A-19D and 20A-20D, and one or more jigs as shown inFIG. 21A-21C. Other combinations of jigs are contemplated.

FIGS. 22A and 22B illustrate an exemplary surgical introducer 800 thatmay be used during the implantation process to introduce the jig to asurgical site during a surgical procedure. The introducer includes ahandle grip 802, a tube 804, a shaft 806, a button 808, a handle core810, and a spring 812.

The shaft 806 includes a proximal end having an annular notch thereinand a distal end that is bifurcated into two cooperating fingers thatare sized and spaced to engage the instrument engaging features 434 ineach side edge of the jig. The button 808 includes a passage throughwhich the proximal end of the shaft 806 passes. Within the passage, thebutton 808 includes a projecting mechanical stop that selectively fitswithin the annular notch on the proximal end of the shaft 806. Thespring 812 biases the button to a position where the stop is disposedwithin the annular notch when the shaft is inserted within the handle.The shaft 806 can be removed by pressing the button 808 to remove thestop from the annular notch.

As can be seen, the tube 804 extends about the shaft 808 and threadedlyconnects to the handle core 810. Threading and unthreading the tube 804results in the tube 804 travelling along the shaft 808. Accordingly, byunthreading the tube 804, the tube 804 can travel along the shaft 808and limit the separation achieved by the fingers of the shaft 808.Likewise, the tube 804 can be used to tighten the fingers onto a jig asdesired.

In use, the posterior stabilization system may be implanted with thefixation rod as part of an orthopedic system. To do this, one or moresurgical exposures are made proximate to an area of the spine or otherbones to be instrumented. The surgical exposures may be open,minimally-invasive, or of other types that are known in surgicalpractice. The vertebrae or other surgical site is prepared, for exampleby retracting tissue, removing tissue, adjusting bony or other tissue,and/or other steps to prepare and fixate a bone or bones. Someembodiments include drilling pilot holes to be used to introduce thebone penetrating features protruding from the jig. This may be doneusing a guide or using other known technique.

Once the surgical site is prepared, the jig may be introduced into thesurgical site. In some embodiments, this may include first selecting asingle jig from a plurality of jigs designed to correspond to particularvertebra. For example, one jig may correspond to C2-C6 vertebrae, whilea separate jig may correspond to a C7 vertebra, and a further jig maycorrespond to a T1 vertebra. With the proper jig selected, the surgeonmay grasp the jig with the surgical instrument 800 along the instrumentengaging features 434. The surgeon may tighten the fingers of theinstrument upon the selected jig by threading the tube 804 until thedistal end of the tube 804 begins to clamp on the fingers of the shaft806. When the jig firmly grasped, the jig is then introduced to thesurgical site by pressing the jig against the lamina of the vertebra. Asthe penetrating features penetrate the vertebra, the lateral boneoutrigger engages the lateral side of the posterior vertebra. The jigmay be before advanced until the bone abutting surface portion 448 ofthe inwardly facing side of the jig engages the lamina along a medialportion while the lateral bone outrigger engages a lateral potion of thevertebra.

With the jig stabilized by the penetrating features in the lamina, thejig may be used as a guide to further prepare the vertebra to receivethe fastener. In some embodiments, a pilot hole or bore is drilled,tapped, punched, or otherwise created in the vertebra for receiving thefastener. In some embodiments, the fastener is a self-drilling orself-tapping screw, and predrilling an opening may be omitted. Inembodiments using the jigs 400, 600, and 650, the hole may be formed inthe lateral mass in the direction of the lateral bone outrigger. Also,depending on the embodiment used, the hole may be formed at an anglecorresponding to the fastener bore, and in one embodiment, may be aboutat an oblique angle in any of the angles described above.

The fastener 404 may then be introduced into the created pilot hole. Anappropriate surgical tool or driver is engaged with the tool-engagingrecess 468 of the fastener 404. As the fastener is tightened to thebone, the force may apply additional loading, further pressing theprotruding features into the bone structures. As such, the lateral boneoutrigger engages the lateral side of the vertebra with its end and/orthe medial side of the lateral bone outrigger.

The jig is now secured in place with the lateral bone outrigger along onthe lateral side of the lateral mass and with the curved surface portionof the inwardly facing side on the lamina. The fastener and thepenetrating features affix the jig in place. With the jig in place, theintroducer instrument 800 may be removed by loosening the tube 804 bythreading it with the handle so that it moves proximally away from thefingers of the shaft 806.

The rod connector 406 is then introduced to the implanted jig. To dothis, the rod connector 406 is oriented so that the flat band 480 canpass through the opening 432 in the outwardly facing surface and intothe attachment feature 433 in the top side. As described above, this maybe accomplished by orienting the flat band 480 into a plane that issubstantially parallel to a plane defined by the edge of the opening 432to the attachment feature 433 in the outwardly facing side of the jig.After passing the pivot head 470 into the attachment feature 433, therod connector 406 may be rotated so that the flat band 480 is not withina plane that is substantially parallel to a plane defined by the edge ofthe opening 432 to the attachment feature 433. The rod connector 406 maythen be pivotably attached to the jig. The surgeon may then make anydesired adjustments to the orientation of saddle 14 with respect to boneanchor 18. For example, the surgeon may rotate or angle the saddle 14relative to the bone anchor 18 to achieve a desired orientation toaccommodate reception of a fixation rod.

The process is then repeated for one or more additional vertebra, eitheradjacent or spaced from the first treated vertebra.

When the rod connectors are properly oriented, a fixation rod may beintroduced into the channels of the receivers 472. The rod may isinserted towards the bottom portion of the receiver at least to a pointso that the set screw 408 can threadingly engage the threaded arms 490of the receiver to hold the rod within the receiver.

When the spine and fixation elements are positioned as the surgeondesires, the rod is locked within the channel of the receiver byadvancing the set screw 408 against the rod. As the set screw 408 isadvanced it urges the rod towards the bottom portion of the receiveruntil the fixation rod is locked in place between the set screw and thebottom of the receiver.

FIGS. 23-28 show an additional embodiment of a system 800. Since thesystem includes many similarities to the other embodiments describedherein, not all features will be re-addressed recognizing that thedescriptions above also apply to the system 800. The system includes ajig 802, a head 804 configured to connect to a rod connector 806, and afastener 808. Like the other embodiments shown and described herein, thejig 802 includes curved or rounded corners and surfaces. The jig 802however is more ergonomically shaped and includes more pronounced curvedor rounded corners and surfaces. In addition, the jig connects with thehead 804 carried on the jig 802, rather than being a part of thereceiver. This will be more apparent in the discussion below.

The jig 802 includes an outwardly facing top side 810, an internallyfacing bottom side 812, two side edges 814 a, 814 b, a medial end 816configured to be medially disposed when implanted on a vertebra, and alateral end 818 configured to be laterally disposed when implanted on avertebra. The outwardly facing side 810 of the jig 802 is substantiallyflat and includes a fastener opening 822 leading to a bore 824 similarto those described above, angled in the manner described with referenceto other embodiments herein, that receives the fastener 808. The jig 802and all other embodiments of jigs disclosed herein, include a fastenerbore where a cross-section through the bore 430 shows the bore 430angled at an angle A1 within a range of about 5-55 degrees for example.In some embodiments, the angle A1 is within a range of about 10-45degrees, and in yet other embodiments, the angle A1 is within a range ofabout 10-41 degrees. In addition, in some embodiments, the jig 802 andall other embodiments of jigs disclosed herein, include a fastener boreangled relative to the side of the jig at an angle A2 within a range ofabout 5-55 degrees for example. In some embodiments, the angle A2 iswithin a range of about 10-45 degrees, and in yet other embodiments, theangle A2 is within a range of about 10-41 degrees. In addition, angle A3representing the angle of the bore looking into the axial plane or fromthe medial end of the jig 802 and all other embodiments of jigsdisclosed herein is within a range of about 5-55 degrees. In someembodiments, the angle A3 is within a range of about 10-45 degrees, andin yet other embodiments, the angle A3 is within a range of about 10-41degrees.

In the exemplary embodiment shown, the outwardly facing side 810 carriesthe head 204, which protrudes from the outwardly facing top side 810.

The internally facing bottom side 812 is curvilinear and, like theembodiments above, includes a relatively tapered surface portion orcurved surface portion 830 disposed toward the medial end 816 of the jig802. Here, the internally facing bottom side 812 also includes alaterally curvilinear surface shaped and arranged to interface with theshape of natural bone. Using the outwardly facing top side 810 as areference, the internally facing bottom side 812 generally curves from aregion of greater thickness at the medial side 816 to a region of lessthickness at the lateral side 818. As best seen in FIG. 23, theinternally facing bottom side 812 includes an edge extending from themedial side 816 in the rounded convex curved surface portion 830, to arounded concave surface portion 832. FIG. 24 shows the opposing side,where the curves are less pronounced, but the curve includes the roundedconvex curved surface portion 830, to the rounded concave surfaceportion 832.

The jig 802 includes rounded edges 836 between the side edges 814 a, 814b and the medial and lateral ends 816, 818 having a larger radius thanthe radius of the rounded edges shown in the drawings of the otherembodiments herein. Here, the rounded edges 836 can be seen in the topview of the jig 802 shown in FIG. 25. In addition, in this embodiment,the side edge 814 incrementally tapers inwardly from the medial side tothe lateral side 818, including both concave and convex sections. Thishelps the jig more fully conform to the underlying bone structure of theunderlying vertebra.

The bottom side 812 is shaped to more closely match the shape of thebone structure and therefore is a non-planar structure. Protruding fromthe bottom surface, the jig 852 includes penetrating features 840 and adifferent lateral bone outrigger 842. In this embodiment the penetratingfeatures 840 are conical pins or small spikes as described above. Thepenetrating features 840 can be used to temporarily hold the modules toa lateral mass bone prior to the creation of fastener holes forreceiving the fastener. The outrigger 842 is substantially centrallydisposed at the lateral end 818 and extends at an oblique angle in thelateral direction from the bottom surface 812, and also at an angle fromthe penetrating features 840. Here, the outrigger 842 extends at anangle within a range of about 20-60 degrees. In some embodiments, therange is about 25-40 degrees, and in some embodiment, the angle is about35 degrees.

The head 804 may be formed of a spherical head portion 850 and a postportion 852, with the spherical head portion 850 disposed on the postportion 852. The head portion 850 and post portion 852 may be formedtogether of a monolithic material, or the post portion 852 may besecured to the head portion 850 in any manner. The post portion 852 maybe fit within a post bore formed in the jig 802. The receiver 806 isconfigured to swivel and pivot on the head portion 850.

The receiver 806 includes a through hole in its bottom portion thatreceives and swivels on the head portion 850 while maintaining aconnection between the receiver 806 and the head portion 850. Additionaldetails of the receiver will not be repeated here since they weredescribed previously.

FIG. 28 shows the system 800 disposed on a vertebra. As can be seen, thesystem 800 abuts against the bone, and the outrigger extends along aside of the bone structure to provide stabilizing support to the jig802. In some embodiments, like those described above, the left and rightjigs configured for respective attachment to left and right sides of thevertebra, are mirror images of each other. That is, the non-symmetricfeatures of any jig are mirrored to the opposing jig.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims. It has obviousimplications in major complex revision and other reconstructive hiparthroplasty procedures.

I claim:
 1. An implantable body for a posterior stabilization systemcomprising: a lateral end, a medial end, an inwardly facing surface, andan outwardly facing surface, the inwardly facing surface having abone-abutting portion disposed proximate the medial end and configuredto abut against a lamina when the body is implanted along a vertebra; alateral bone outrigger extending from the inwardly facing surfaceadjacent the lateral end, the lateral bone outrigger having abone-abutting surface along a medial portion disposed to abut against alateral mass of the vertebra when the body is implanted along avertebra, the lateral bone outrigger having a first height; apenetrating feature extending from the inwardly facing surface betweenthe bone-engaging portion of the inwardly facing surface and the lateralbone outrigger, the penetrating feature having a second height less thanthe first height; and a fastener bore extending through the body fromthe inwardly facing surface to the outwardly facing surface, thefastener bore being angled toward the lateral bone outrigger.
 2. Theimplantable body of claim 1, wherein the inwardly facing surfacecomprises a tapered surface and a flat surface, the bone-abuttingportion being formed of the tapered surface.
 3. The implantable body ofclaim 1, wherein the inwardly facing surface comprises a curved surfaceand a flat surface, the bone-abutting portion being formed of the curvedsurface.
 4. The implantable body of claim 1, wherein the bone-abuttingsurface on the lateral bone outrigger is a rounded surface.
 5. Theimplantable body of claim 1, wherein the fastener bore is angled at anangle within the range of about 20-55 degrees when measured incross-section.
 6. The implantable body of claim 5, wherein the fastenerbore is angled at an angle within the range of about 20-55 degrees asmeasured from a side edge.
 7. The implantable body of claim 6, whereinthe second height from the inwardly facing surface is within a range ofabout 4-8 mm.
 8. The implantable body of claim 6, wherein the lateralbone outrigger is cylindrically shaped and is disposed proximate only aportion of the lateral end.
 9. The implantable body of claim 6, whereinthe lateral bone outrigger is disposed in a corner of the inwardlyfacing surface.
 10. The implantable body of claim 6, wherein the lateralbone outrigger is disposed along a centerline extending from the medialend to the lateral end.
 11. The implantable body of claim 1, wherein thefastener bore is angled so that when the implantable is implanted, thefastener bore forms an angle in the range of 20-55 degrees from thesagittal plane and an angle in the range of 20-55 degrees from the axialplane.
 12. A posterior stabilization system comprising: an implantablebody shaped to abut against a lateral mass of a cervical vertebracomprising: a lateral end, a medial end, an inwardly facing surface andan outwardly facing surface, the inwardly facing surface having abone-abutting portion disposed proximate the medial end configured toabut against a lamina when the body is implanted along a vertebra; alateral bone outrigger extending from the inwardly facing surfaceadjacent the lateral end, the lateral bone outrigger having abone-abutting surface along a medial portion disposed to abut against alateral mass of the vertebra when the body is implanted along avertebra; a penetrating feature extending from the inwardly facingsurface between the bone-engaging portion of the inwardly facing surfaceand the lateral bone outrigger; and a fastener bore extending throughthe body from the inwardly facing surface to the outwardly facingsurface; a rod receiving portion sized to receive a fixation rod, therod receiving portion being pivotably attached to the body; and afastener sized to extend through the bore and penetrate the lateral massof the vertebra.
 13. The system of claim 12, wherein the inwardly facingsurface comprises a curved surface and a flat surface, the bone-abuttingportion being formed of the curved surface.
 14. The system of claim 12,wherein the bone-abutting surface on the lateral bone outrigger is arounded surface.
 15. The system of claim 12, wherein the fastener boreis angled at an angle within the range of about 20-55 degrees whenmeasured in cross-section.
 16. The system of claim 12, wherein thefastener bore is angled at an angle within the range of about 20-55degrees as measured from a side edge.
 17. A non-pedicle based fixationsystem, comprising a first posterior stabilization system comprising: afirst body shaped to abut against a lateral mass of a first cervicalvertebra, the first body comprising: a lateral end, a medial end, aninwardly facing surface, and an outwardly facing surface, the inwardlyfacing surface having a bone-abutting portion disposed proximate themedial end and configured to abut against a lamina when the body isimplanted along a vertebra; a lateral bone outrigger extending from theinwardly facing surface adjacent the lateral end, the lateral boneoutrigger having a bone-abutting surface at along a medial portiondisposed to abut against a lateral mass of the vertebra when the body isimplanted along a vertebra, the lateral bone outrigger having a firstheight; and a penetrating feature extending from the inwardly facingsurface between the bone-engaging portion of the inwardly facing surfaceand the lateral bone outrigger, the penetrating feature having a secondheight less than the first height; and a first rod receiving portionshaped to receive a fixation rod, the rod receiving portion beingdisposed closer to the lateral end than the medial end; a secondposterior stabilization system comprising a second body shaped to abutagainst a lateral mass of a second cervical vertebra, the first bodycomprising a lateral end, a medial end, an inwardly facing surface, andan outwardly facing surface, the inwardly facing surface having abone-abutting portion disposed proximate the medial end and configuredto abut against a lamina when the body is implanted along a vertebra; alateral bone outrigger extending from the inwardly facing surfaceadjacent the lateral end, the lateral bone outrigger having abone-abutting surface at along a medial portion disposed to abut againsta lateral mass of the vertebra when the body is implanted along avertebra, the lateral bone outrigger having a first height; apenetrating feature extending from the inwardly facing surface betweenthe bone-engaging portion of the inwardly facing surface and the lateralbone outrigger, the penetrating feature having a second height less thanthe first height; and a second rod receiving portion shaped to receivethe fixation rod, the rod receiving portion being disposed closer to thelateral end than the medial end; and a fixation rod disposed within thefirst and second rod receiving portions.
 18. The system of claim 17,wherein the first body comprises a fastener bore extending through thebody from the inwardly facing surface to the outwardly facing surface,the fastener bore being angled toward the lateral bone outrigger. 19.The system of claim 18, wherein the first body includes a side edge, thefastener bore being angled away from the side edge.
 20. The system ofclaim 19, wherein the fastener bore is angled toward the lateral boneoutrigger within an angle range of about 20-55 degrees, and the fastenerbore angled away from the side edge within an angle range of about 20-55degrees.